If you are buying a cheap drill/driver for £15-20, then so long as it works for long enough to do three or four jobs, then fair enough. However, if you have paid a lot more for a "professional" drill/driver, then I would expect at least a 1-year replacement warranty, if not longer.
In my experience, the cheaper (and sometimes no-so-cheap) drills using Ni-Cd batteries are not, by a long chalk, as efficient or long-lasting as those using the newer Lithium-ion batteries.
I was buying two cheap drills a year and cussing when the batteries failed to hold their charge. My last purchase, over a year ago was Li-ion, and it's still as good as when new!